Traditional approaches have greatly refined our understanding of the molecular mechanisms involved in the regulation of flux through metabolic pathways. In recent years, however, progress has been slow and complete understanding of regulatory mechanisms as yet unattained. Recombinant DNA technology could revolutionize the study of metabolism and related biochemical problems. Several laboratories are already using this technology to analyze regulation of the expression of key enzymes in metabolism. Studies of the relationship between protein structure and enzymic and/or regulatory function also are being initiated. These are just the beginning. Rapid sequencing techniques for cloned DNAs make it feasible to determine the entire amino acid sequence for any enzyme. Site-specific mugtagenesis will enable investigators to prepare enzymes of any amino acid sequence. Expression of the normal and mutant enzymes in heterologous host will allow the production of quantities of protein sufficient for physical and kinetic analyses. Furthermore, gene transfer techniques will allow analysis of the function of normal and mutant enzymes in situ in the metabolic pathways of isolated cells or whole animals. It should be possible to engineer a metabolic pathway "to order." Despite the enormous potential of these approaches, however, many investigators interested in metabolic regulation have been reluctant to initiate studies using recombinant DNA techniques. Conversely, many molecular biologists are unaware of the fascinating metabolic problems which still require solution. In this symposium we propose to bring together three groups of scientists: (1) those interested in metabolic regulation but not yet using the recombinant DNA technology, (2) those already using this technology to study regulation of "metabolically" interesting genes, and (3) those involved in the development and use of the techniques of gene transfer, site-specific mutation and expression of cloned genes in heterologous cells. The resulting exchange of information among these groups should have a significant impact on the direction of future studies of metabolism.